1. Field of the Invention
This invention relates generally to a portable machining lathe, and in particular to a mechanism for preventing deflection of the guide rails of a journal turning lathe used for cutting and finishing relatively long spans of large diameter pipes.
2. Description of the Related Art
Split frame journal turning lathes of the type described herein are known in the art. The journal turning lathe generally comprises first and second end brackets which are concentrically mounted on a cylindrical work piece at a predetermined axial spacing. A plurality of guide rails extend between the first and second end brackets in parallel relations to the cylindrical work piece. The journal turning lathe assembly further has a relatively heavy clamshell lathe assembly having a first and second semicircular segments that are designed to be joined together to form an annular assembly for encircling a shaft or pipe to be machined. The assembly includes a stationary ring, and a rotatable ring abutting the stationary ring. The rotatable ring is made of steel and on its peripheral surface and is journaled to the stationary portion for rotation about a concentrically disposed pipe or shaft to be machined. A motor is attached to the stationary assembly and includes a drive gear designed to mesh with the spur gear on the rotatable segment of the pipe lathe. Also, a heavy tool block for supporting a cutting tool is mounted on the rotatable segment. The cutting tool is adapted to be advanced in incremental steps in a radial direction against the pipe to be machined upon each orbit of the ring gear about the work piece.
A problem has heretofore existed that the guide rails carrying the clamshell assembly may bend or deflect under the weight of the clamshell lathe assembly as the midpoint of the guide rails is approached. As the journal turning lathe progresses to the center of the cylindrical work piece, the weight of the lathe assembly causes the supporting structure to sag at the center. This sagging, in turn, results in uneven machining of the work piece. It is the purpose of this invention to remedy this problem.
The present invention comprises an intermediate support brace for a journal turning lathe for supporting the guide rails and cylindrical work piece. The support brace includes a somewhat U-shaped frame, and a first and second clamping member. The U-shaped frame has a series of semi-circular notches cut into the surface of the frame along the thickness dimension thereof. The U-shaped frame is lifted onto the journal turning lathe, and the guide rails of the lathe are received in the concaved notches in the U-shaped frame. The clamping members each have a pair of corresponding inverted semicircular notches which are placed over the top half of each guide rail. The concaved notches of the frame cooperate with the inverted notches of the clamping members to encircle and trap the guide rails. The frame and first clamping member have a series of regularly spaced threaded apertures which locator members pass through to center the pipe in the frame.
The primary advantage of the present invention is that it provides support for the guide rails preventing any appreciable sag thereof due to the weight of the clamshell assembly of the journal turning lathe that are suspended on the guide rails.
Another feature of the present invention is that it is relatively easy to affix to and remove the support brace from the journal turning lathe to allow the clamshell assembly to traverse the entire length of the work piece being machined.
An additional advantage of the present invention is that it is portable and can be taken to a variety of job sites along with the journal turning lathe.
For a better understanding of the invention, and of the advantages obtained in its use, reference should be made to the drawings and the accompanying descriptive material, in which there is illustrated and described a preferred embodiment of the invention.